Thyroid nodules and differentiated thyroid cancer: update on the Brazilian consensus
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Thyroid consensus
Thyroid nodules and differentiated
thyroid cancer: update on
the Brazilian consensus
Nódulo tireoidiano e câncer diferenciado de
tireoide: atualização do consenso brasileiro
Pedro Weslley Rosário1, Laura S. Ward2, Gisah A. Carvalho3, Hans Graf3,
Rui M. B. Maciel4, Léa Maria Z. Maciel5, Ana Luiza Maia6, Mário Vaisman7
ABSTRACT
1
Serviço de Endocrinologia e
Instituto de Ensino e Pesquisa,
Thyroid nodules are frequent findings, especially when sensitive imaging methods are used. Al-
Santa Casa de Belo Horizonte, though thyroid cancer is relatively rare, its incidence is increasing, particularly in terms of small
Belo Horizonte, MG, Brazil tumors, which have an uncertain clinical relevance. Most patients with differentiated thyroid
2
Laboratório de Genética Molecular
do Câncer e Endocrinologia,
cancer exhibit satisfactory clinical outcomes when treatment is appropriate, and their morta-
Departamento de Clínica Médica, lity rate is similar to that of the overall population. However, relapse occurs in a considerable
Faculdade de Ciências Médicas, fraction of these patients, and some patients stop responding to conventional treatment and
Universidade Estadual de Campinas
(FCM/Unicamp), Campinas, SP, Brazil
eventually die from their disease. Therefore, the challenge is how to identify the individuals
3
Serviço de Endocrinologia who require more aggressive disease management while sparing the majority of patients from
e Metabologia, Universidade unnecessary treatments and procedures. We have updated the Brazilian Consensus that was
Federal do Paraná (SEMPR/
UFPR), Curitiba, PR, Brazil
published in 2007, emphasizing the diagnostic and therapeutic advances that the participants,
4
Disciplina de Endocrinologia, representing several Brazilian university centers, consider most relevant in clinical practice. The
Departamento de Medicina, Escola formulation of the present guidelines was based on the participants’ experience and a review
Paulista de Medicina, Universidade
Federal de São Paulo (EPM/
of the relevant literature. Arq Bras Endocrinol Metab. 2013;57(4):240-64
Unifesp), São Paulo, SP, Brazil Keywords
5
Divisão de Endocrinologia,
Thyroid nodules; thyroid cancer; Brazilian consensus; update
Departamento de Clínica Médica,
Faculdade de Medicina de
Ribeirão Preto, Universidade
de São Paulo (FMRP-USP),
RESUMO
Ribeirão Preto, SP, Brazil Nódulos tireoidianos são muito frequentes, sobretudo quando se empregam métodos sensí-
6
Setor de Tireoide, Serviço de
veis de imagem. Embora o câncer seja proporcionalmente raro, sua incidência vem aumen-
Endocrinologia, Hospital de Clínicas
de Porto Alegre, Universidade tando, especialmente de tumores pequenos, cuja evolução clínica é incerta. A maioria dos pa-
Federal do Rio Grande do Sul (HC- cientes com carcinoma diferenciado de tireoide evolui bem quando adequadamente tratada,
UFRGS), Porto Alegre, RS, Brazil
com índices de mortalidade similares à população geral. Por outro lado, um percentual não
7
Serviço de Endocrinologia,
Hospital Universitário Clementino desprezível apresenta recidivas e alguns eventualmente não respondem às terapias convencio-
Fraga Filho, Faculdade de nais, evoluindo para óbito. Assim, o desafio é distinguir os pacientes merecedores de condutas
Medicina, Universidade Federal
mais agressivas e, ao mesmo tempo e não menos importante, poupar a maioria de tratamen-
do Rio de Janeiro (HUCFF/UFRJ),
Rio de Janeiro, RJ, Brazil tos e procedimentos desnecessários. Atualizamos o Consenso Brasileiro publicado em 2007,
ressaltando os avanços diagnósticos e terapêuticos que os participantes, de diferentes Centros
Correspondence to: Universitários do Brasil, consideram mais relevantes para prática clínica. A elaboração dessas
Pedro Weslley Rosário diretrizes foi baseada na experiência dos participantes e revisão da literatura pertinente. Arq Bras
Instituto de Ensino e Pesquisa,
Santa Casa de Belo Horizonte Endocrinol Metab. 2013;57(4):240-64
Rua Domingos Vieira, 590
30150-240 – Belo Horizonte, MG, Descritores
Copyright© ABE&M todos os direitos reservados.
Brazil Nódulo de tireoide; câncer de tireoide; consenso brasileiro; atualização
pedrorosario@globo.com
Received on Apr/24/2013
Received on Apr/25/2013
240 Arq Bras Endocrinol Metab. 2013;57/4Thyroid nodules and differentiated thyroid cancer
INTRODUCTION APPROACH TO PATIENTS WITH THYROID
S everal thyroid diseases may present as nodules. NODULES
According to population-based studies conduc-
What clinical information must be collected?
ted with adults in iodine sufficient areas, approxima-
tely 4 to 7% of women and 1% of men exhibit palpa- With regard to patients with thyroid nodules, a tho-
ble thyroid nodules (1,2). However, the prevalence of rough clinical interview and physical examination must
nodules indicated by ultrasound exams (US) is subs- be performed. Although these methods are most often
tantially higher, reaching up to 68% of the population neither sensitive nor specific, some of the data they pro-
(3,4); such high frequencies are usually found among vide are indicative of a higher risk of malignancy (5,10-
older women (5). Although most thyroid nodules are 14) (Table 2).
benign, the possibility of a malignancy must be ruled
out; 95% of malignant tumors are well-differentiated Table 2. Data from the clinical history and physical examination that
carcinomas (6,7). suggest a greater risk of malignancy in thyroid nodules
Although the current incidence of thyroid cancer Male gender; age < 20 or > 70 years old; history of exposure to ionizing
radiation or neck radiotherapy in childhood or adolescence; previous diagnosis
is not higher than 24 cases per 100,000 people (7),
of thyroid cancer treated by means of partial thyroidectomy
the incidence has been increasing in recent years (7)
Family (first degree) history of thyroid cancer, especially when affecting two or
to become the fourth most common type of malignant more relatives in the case of differentiated carcinoma
tumor among Brazilian women (8). This increased in- Hereditary syndromes such as multiple endocrine neoplasia type 2 (MEN II),
cidence is mostly associated with a greater number of Cowden syndrome, Pendred syndrome, Werner syndrome, Carney complex,
and familial adenomatous polyposis
small papillary carcinomas (6).
Fast-growing or large nodules with compressive symptomsa
The recommendations described here were pre-
pared according to the model provided by Pro Hard nodules, adhered to deep tissues, with little mobility; associated with
paralysis of the ipsilateral vocal cord; or cervical lymphadenopathya
ject Guidelines (Projeto Diretrizes) by the Brazilian
Nodules incidentally detected on FDG-PET (focal uptake) in cancer patients
Medical Association (Associação Médica Brasileira –
a
Confirmation of these data as being suspicious of malignancy requires comparison with the
AMB) and Federal Council of Medicine (Conselho results of imaging exams.
Federal de Medicina – CFM) (9), which is a nation-
wide initiative already known to the Brazilian medical As will be subsequently shown, nodules that are
and academic communities. Consistently, the recom- large or are considered suspicious upon a US exam
mendation levels or the strength of evidence degrees must be subjected to fine needle aspiration (FNA)
employed by that model were used, as described in biopsy, regardless of the patient’s clinical history. Con-
Table 1 (9). versely, nodules that are small and are not considered
Following the selection of participants with estab- suspicious upon US require further investigation only
lished academic activity and clinical experience relat- in patients with high clinical risk of malignancy, in
ed to the thyroid, the clinical questions that ground- which case the personal and family history become sig-
ed the recommendations were elaborated upon. The nificantly relevant.
corresponding literature was located in the Med-
Line-PubMed, EMBASE, and SciELO-LILACS da- Recommendation 1
tabases. Individuals with a personal or family history of thyroid
cancer, a history of exposure to radiation in childhood
or adolescence, or nodules incidentally discovered on
Table 1. Recommendations according to the level of evidence (9) fluorodeoxyglucose positron emission tomography
Recommendation Strength of evidence (FDG-PET; focal uptake) are considered to be at high
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Experimental and observational studies with better risk for thyroid malignancy (Recommendation B).
A consistency
Experimental and observational studies with less What are the recommended laboratory tests?
B consistency
C Case reports (non-controlled studies) Serum thyroid-stimulating hormone (TSH)
Opinion lacking critical assessment, based on As clinical assessment is not always indicative of thyroid
D consensus, physiological studies, or animal models
dysfunction, TSH levels must be measured.
Arq Bras Endocrinol Metab. 2013;57/4 241Thyroid nodules and differentiated thyroid cancer
Whenever hyperfunction is detected, even when it is What is the role of the imaging methods?
subclinical, thyroid scintigraphy, preferably with radio- Neck ultrasound
active iodine (RAI), is indicated to establish whether
the nodule has high or low uptake. In approximately US is an excellent method for the detection of thyroid
10% of the patients with solitary nodules, TSH is sup- nodules, with a sensitivity of approximately 95% (24),
pressed and the nodule has high uptake. In such cases, which is higher than other sophisticated methods such
FNA is unnecessary because this type of nodule is ex- as computed tomography (CT) and magnetic resonan-
ceptionally malignant (5,15). ce imaging (MRI) and often results in modifications of
When TSH levels are elevated, the levels of anti- decisions exclusively based on the findings upon palpa-
thyroid peroxidase (anti-TPO) antibodies may be mea- tion (25). US allows for the assessment of the nodule
sured to confirm a diagnosis of autoimmune thyroiditis. size, composition, and characteristics. In addition, US
When the US shows a well-defined nodule, the criteria might detect suspicious lymph nodes in the neck and
to indicate an FNA are the same in patients with and eventually the compression or invasion of thyroid adja-
without Hashimoto’s thyroiditis (16). Although some cent structures (26).
studies have shown a direct correlation between serum US is also used in diagnostic (e.g., directed FNA)
TSH levels and risk of malignancy in thyroid nodules and therapeutic (e.g., cyst aspiration, ethanol injec-
and even with initial staging (17,18), the currently tion, laser therapy) procedures and to monitor nodule
available data do not support the indication of any par- growth.
ticular approach of patients with thyroid nodules and Some US findings are associated with increased risk
normal-to-high or high TSH levels. of malignancy. Such findings include hypoechogenicity
(especially if there is marked hypoechogenicity); micro-
Serum calcitonin and thyroglobulin levels calcifications; irregular margins; predominantly or ex-
clusively central vascularization detected by Doppler;
Several studies have assessed the utility of serum (basal
larger anteroposterior diameter compared with the
and stimulated) calcitonin for early diagnosis of spo-
transverse diameter (27-31); and, more specifically, the
radic medullary thyroid carcinoma (MTC) in patients
detection of lymph nodes of the neck with suspicious
with thyroid nodules (19-22). However, the interpreta-
characteristics. Nevertheless, US findings alone do not
tion of calcitonin (basal and stimulated) results and the
allow for absolute differentiation between benign and
cost-benefit ratio are controversial and may be more
malignant lesions (24).
interesting in patients who have small nodules and are
Assessment of the nodule elasticity (elastography)
over 40 years of age (21). The sensitivity and specificity
demonstrates greater rigidity in malignant tumors. Al-
of the serum thyroglobulin (Tg) levels are relatively low
though elastography cannot replace conventional US,
for the diagnosis of thyroid cancer (23).
when performed together (elastography plus US), the
sensitivity and specificity of the assessment improve
Recommendation 2
(32). In addition, the instances in which elastography
Serum TSH levels must be measured at the initial assess- might be clinically decisive when combined with US
ment, primarily to eliminate the possibility of autonomous must still be established as well as its limitations and
or hyperfunctioning nodules (Recommendation A). potential means of minimizing these limitations (33).
Recommendation 3 Recommendation 5
Except for patients with clinical suspicion or family his- Neck US must be performed in all patients with thyroid
tory of MTC or multiple endocrine neoplasia type 2 nodules (Recommendation A).
(MEN II), measurement of serum calcitonin is not ne-
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cessary (Recommendation C). Computed tomography, magnetic resonance imaging,
and positron emission tomography
Recommendation 4
Neither CT nor MRI can differentiate between benign
Serum Tg levels are not recommended to distinguish and malignant lesions as well as US; therefore, these
between benign and malignant thyroid nodules (Re- methods are seldom indicated for the assessment of
commendation B). thyroid nodules. However, these imaging modalities
242 Arq Bras Endocrinol Metab. 2013;57/4Thyroid nodules and differentiated thyroid cancer
are useful in the assessment of substernal goiter and the Nevertheless, the high frequency of microcarcinomas
compression or invasion of adjacent structures, such as found only in autopsies (39), their low rate of progres-
the trachea (34). Although 18FDG-PET is useful in the sion even when untreated (40,41), and the fact that the
differentiation between benign and malignant lesions probability of a cure is not affected when treatment is
(35), this technique is still not readily accessible and is delayed until the tumor exhibits growth (40) minimize
quite expensive. In addition, this sophisticated techni- the concerns associated with the detection of microcar-
que does not allow for the dismissal of FNA and might cinomas. Consistently, the investigation focuses on the
be more useful for the cases with undetermined cyto- diagnosis of carcinomas larger than 1 cm.
logy (35).
Recommendation 8
Recommendation 6 When hyperfunctioning or purely cystic nodules have
CT, MRI, and FDG-PET are seldom necessary for the been ruled out, the indication for FNA is based on the
assessment of thyroid nodules (Recommendation B). patient’s clinical history, nodule size, and US findings
(Recommendation B). These indications are summari-
Isotope scintigraphy zed in table 3.
Scintigraphy with radionuclides is important to deter-
mine whether nodules are hyperfunctioning. Hyper- Table 3. Indications for FNA in patients with thyroid nodules (except for
functioning nodules with or without extra-nodular hyperfunctioning or purely cystic nodules)
suppression are exceptionally malignant (5,15). Scin- Nodule size FNA indicated
tigraphy may be performed with 131I or 123I or 99mTc < 5 mm Not indicated
pertechnetate. The iodine radioisotopes are absorbed ≥ 5 mm Patients with high risk of malignancy
and organified by the thyroid and are the preferred iso- or suspicious nodule on USa
types because 3 to 8% of nodules that are hyperfunctio- ≥ 10 mm Solid hypoechoic noduleb
ning when mapped with 99mTc scans are hypofunctio- ≥ 15 mm Solid iso- or hyperechoic noduleb
ning with iodine (36). Scintigraphy is also indicated for ≥ 20 mm Complex or spongiform noduleb
nodules with cytology, which is suggestive of follicular Nodule with apparent extrathyroidal All
tumor in patients with normal low or low TSH, if it was invasion
not performed earlier (37). Suspicious lymph node upon US Lymph node FNA
a
In nodules < 10 mm without apparent invasion or suspicious lymph nodes, monitoring with
US, with FNA when the nodule exceeds 10 mm is considered acceptable.
Recommendation 7 b
Even without suspicious US findings.
Thyroid scintigraphy is indicated when a functioning
nodule is suspected (subnormal TSH) (Recommen-
dation A) or cytology is suggestive of follicular tumor What approaches follow from cytology?
(Recommendation B). The National Cancer Institute (NCI, USA) held a mul-
tidisciplinary conference, which established that the
When is a fine needle aspiration biopsy indicated? cytopathology results must reflect the cytopathologist’s
FNA is the best available method to distinguish be- diagnostic impression in a succinct and clear manner
tween benign and malignant lesions (5), even in the without leaving room for interpretative misunderstan-
case of nodules smaller than 1 cm (3) or larger than dings. The classification system suggested for that pur-
4 cm (38). In addition, FNA is an easy and low-cost pose, known as Bethesda System (42), is described in
outpatient procedure that is virtually devoid of serious table 4. The approach of patients based on the cytology
complications. Nevertheless, we emphasize the im- results is depicted below (Figure 1).
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portance of having an experienced physician perform
this procedure as well as the necessity of an experien- Recommendation 9
ced cytopathologist who can accurately analyze the Surgery is recommended when cytology results indi-
biopsy material. cate a suspicious malignancy (Bethesda category V)
Thyroid nodules smaller than 1 cm represent micro- or confirmed malignancy (Bethesda category VI) (Re-
carcinomas in a considerable percentage of cases (3). commendation A).
Arq Bras Endocrinol Metab. 2013;57/4 243Thyroid nodules and differentiated thyroid cancer
Table 4. Bethesda system of thyroid cytopathology reports of malignancy or nodules larger than 2 cm. Patients
Category with nodules ≤ 2 cm and low clinical and ultrasonogra-
I Non-diagnostic or unsatisfactory sample phic suspicion of cancer should be monitored (Recom-
II Benign mendation C).
III Atypia/follicular lesion of undetermined significance
IV Follicular tumor or suspicious for follicular tumor Recommendation 12
V Suspicious malignancy
When the biopsy sample is unsatisfactory for cytologi-
VI Malignant
cal analysis (Bethesda category I), it is recommended to
repeat the US-directed FNA 3 to 6 months later (Re-
Recommendation 10
commendation B). When the results persist, surgery is
When the cytology results are indicative of a follicular indicated for patients with high clinical or ultrasono-
tumor (Bethesda category IV), scintigraphy is useful for graphic suspicion of malignancy or nodules larger than
decision making. Removal of hyperfunctioning nodules 2 cm. Patients with nodules ≤ 2 cm and low clinical and
is not mandatory; however, hypofunctioning nodules ultrasonographic suspicion of cancer should be moni-
remain an indication for surgery (Recommendation B). tored (Recommendation C).
Some studies (43-45) have shown that when cyto
Recommendation 11 logy is benign but the nodule exhibit a combination
When cytology indicates follicular lesion or atypia with of US findings compatible with malignancy, repetition
undetermined significance (Bethesda category III), it is of the FNA can be useful, regardless of the nodule
recommended to repeat the FNA 3 to 6 months later. growth, as the rate of malignancy in such discordant
When the results persist, surgery is indicated for pa- cases is substantially higher than the traditional false-
tients with high clinical or ultrasonographic suspicion negative rate of FNA, which varies from 1 to 3% (42).
Thyroid nodule (except for pregnart women)
Normal or high TSH Low TSH
FNA not indicated FNA | or 123| scintigraphy
131
Suspicious for malignancy Follicular AUS/FLUS b Benign Hypofunctioning Hyperfunctioning
or malignant neoplasm b Unsatisfactory nodule: FNA nodule
Surgery a 131
| or 123| scintigraphy Repeat FNA 3-6 Treatment or
months later monitoring with US c
Hypofunctioning Hyperfunctioning Same result
nodule: surgery a nodule
Nodule ≤ 2 cm, Nodule > 2 cm or
low clinical and high clinical or
US suspicion US suspicion
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Monitoring with Sugery a
US c
AUS, atypia of uncertain significance; FLUS, follicular lesion of uncertain significance.
a
See the extent of surgery in R14, R15, R28, R30-32.
b
When available, molecular markers are useful.
c
See R24-26.
Figure 1. Suggested approach in patients with thyroid nodules.
244 Arq Bras Endocrinol Metab. 2013;57/4Thyroid nodules and differentiated thyroid cancer
18
FDG-PET helps rule out malignancy in thyroid Recommendation 15
nodules with undetermined cytology (35); however, as it Lobectomy is considered sufficient in unilateral and
is expensive and not readily accessible, 18FDG-PET is not sporadic nodular disease when (i) the nodule ≤ 4 cm,
recommended as a routine procedure in this context. cytology is undetermined, and the clinical and ultraso-
nographic suspicion of malignancy is low or (ii) cytolo-
What is the utility of molecular markers? gy is unsatisfactory (Recommendation B).
Several molecular markers have been assessed, espe- As the pre-test malignancy risk is modified when
cially with regard to thyroid nodules with undetermi- molecular markers or FDG-PET scans are used, the ex-
ned cytology. Markers such as HBME, galectin, and tent of surgery described above may be modified based
CK19, among others, can be measured by any labo- on their results.
ratory that performs routine immunohistochemical
tests. Such markers are helpful in the identification What is the approach in children and adolescents?
of malignant tumors, particularly papillary carcinomas
(46). Although their sensitivity reaches 0.85 to 0.93,
Recommendation 16
their specificity varies from 0.43 to 0.71 at most (47). The recommendations described above also apply in
Mutations in specific genes (such as BRAF V600E and the case of thyroid nodules in childhood and adoles-
RAS) or gene rearrangements (such as RET/PTC and cence (Recommendation B).
PAX8-PPARy) can also contribute to the identifica- In pregnant women, scintigraphy with isotopes is
tion of malignancy (48). Unfortunately, a panel with contraindicated. Surgery increases the risk of miscarriage
these four markers (BRAF, RAS, and rearrangements in the first trimester and of premature birth in the third
RET/PTC and PAX8/PPARy) fails to identify 36% of trimester; therefore, surgery is safest when performed in
malignant cases (sensitivity of 64%) in clinical practice the second trimester (52). In addition, delay of the onset
(49). Other markers, such as microRNAs, are being of treatment of differentiated carcinoma diagnosed in
investigated (50). Recently, a novel test designed to pregnancy does not appear to be associated with disease
rule out malignancy exhibited a high negative predic- progression or interference with the probability of a cure
tive value (95%) in nodules with undetermined cyto- (53). Based on those premises, the recommendations in
logy (51). nodules detected during pregnancy are as follows:
Recommendation 13 Recommendation 17
Molecular markers are helpful in defining the nature Pregnant women with large nodules, apparent invasion,
of thyroid nodules, especially those with undetermined or suspicious lymph nodes on US must be subjected to
cytology (Bethesda category III or IV) (Recommen- FNA (Recommendation A). In the remainder of cases,
dation A). Consistently, the surgical recommendations when TSH levels are spontaneously suppressed, follow
above (especially R10 and R11) may be modified when up with US is recommended (Recommendation B).
molecular markers are used. When TSH levels are normal or high, FNA is indicated
as described in table 3; however, monitoring with US
What should the extent of the surgery be when (without FNA) is also acceptable (Recommendation B).
malignancy is undetermined?
Recommendation 18
Recommendation 14 When FNA is not performed in the initial assessment,
A total thyroidectomy is recommended under the follo- it must be performed when the nodule exhibits signi-
wing conditions: (i) when a nodular disease is bilateral; ficant growth in the course of pregnancy (Recommen-
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(ii) when a nodular disease is associated with radiation; dation B).
(iii) when the cytology is indicative of a suspicious ma-
lignancy; and (iv) when the cytology is undetermined Recommendation 19
and the nodule is > 4 cm or ≤ 4 cm but is associated In case of undetermined cytology, surgery may be indi-
with high clinical or US suspicion of cancer (Recom- cated in the second trimester if there is significant no-
mendation B). dule growth (Recommendation B). Surgery can also be
Arq Bras Endocrinol Metab. 2013;57/4 245Thyroid nodules and differentiated thyroid cancer
performed in the second trimester when the cytology How should the patients not subjected to surgery be
indicates a suspicious malignancy or malignancy and monitored?
the tumor exhibits significant growth or the disease is Although the malignancy risk of nodules without indi-
in an advanced stage (Recommendation B). TSH levels cation for FNA (63) or surgery is low [benign cytolo-
must be kept low (< 0.5 mIU/L) in patients with ma-
gy (5,42), small nodules with unsatisfactory cytology
lignant cytology until surgery (Recommendation C).
(64,65) or undetermined follicular lesions/atypia, and
non-suspicious clinical history and US], monitoring
Recommendation 20
with US is recommended to detect eventual nodule
Following delivery, patient management should be re- growth, although its low specificity for a malignancy
assessed according to the usual recommendations (Re- diagnosis is an acknowledged fact (44,66). The interval
commendation A). between the US tests varies from 6 to 24 months and
is defined depending on the number of previous asses-
When indicated, what are the non-surgical sments and changes in the nodule size in relation to
therapeutic options for benign nodular disease? previous US(s).
Several studies have suggested that the use of levo-
thyroxine (T4) with consequent reduction of TSH le- Recommendation 24
vels suppresses nodule growth (54-56). However, the When an FNA is not performed in the initial assess-
adverse effects of hormone therapy on the cardiovascu- ment, it must be performed when the nodules meet the
lar system and bone metabolism (57,58) limit its use. criteria listed in Table 3 (Recommendation B).
Focal destruction by means of sclerotherapy with
ethanol or laser photocoagulation can be considered Recommendation 25
in patients with benign solitary nodules (59,60). When
In cases of benign cytology, FNA must be repeated
the main problem is thyroid hyperfunction caused by an
when the nodules exhibit significant growth (> 50%
autonomous nodule, long-term anti-thyroid drug treat-
compared with the initial volume; Recommendation
ment is an interesting option in elderly patients (60).
C).
In several patients with multinodular goiter, iodine
uptake is not homogeneous and is relatively low due to
the presence of inactive nodules (i.e., “hypofunctioning”
Recommendation 26
on scintigraphy) or suppression of the paranodular tissue. Surgery must be considered for nodules that progress
As such areas concentrate 131I very weakly, the efficacy of over time and whose initial cytology was undetermined
this treatment is compromised. The use of low doses of or unsatisfactory (Recommendation B).
recombinant TSH significantly increases 131I uptake in
such patients and allows even low activities to efficiently
reduce the goiter size by 30 to 50% in one year (60-62).
MANAGEMENT OF DIFFERENTIATED THYROID
CARCINOMA
Recommendation 21 In Brazil and worldwide, sensitive imaging methods
Suppressive treatment with T4 is not recommended for such as US are becoming increasingly accessible to an
thyroid benign nodular disease (Recommendation B). aging population, thus increasing the number of indi-
viduals diagnosed with small nodules that, even when
Recommendation 22 confirmed as malignant, exhibit uncertain progression.
The high frequency of carcinomas that are only found
Sclerotherapy with alcohol can be considered for cystic
during autopsies (39) and prospective studies conduc-
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or predominantly cystic nodules (Recommendation B).
ted with Japanese patients with microcarcinomas not
subjected to surgery (40,41) suggest that a large num-
Recommendation 23
ber of these tumors never exhibit clinical progression,
Treatment of a nontoxic multinodular goiter with 131I which appears to account for the low mortality rate of
can be optimized through previous administration of differentiated thyroid carcinomas (DTCs) in spite of its
low doses of recombinant TSH (Recommendation B). increased incidence (6,7).
246 Arq Bras Endocrinol Metab. 2013;57/4Thyroid nodules and differentiated thyroid cancer
Most patients with DTC exhibit good outcomes in case of clinical or ultrasonographic suspicion of inva-
when they are appropriately treated. However, relapse sion of adjacent structures (69,70). The use of iodin-
occurs in a significant percentage of cases, and some ated contrast should be avoided; however, when iodin-
of these cases stop responding to conventional treat- ated contrast is necessary to better assess the extent of
ment and eventually die from their disease. The chal- disease, the therapy with 131I, when indicated, must be
lenge, therefore, is to identify the individuals who re- deferred for at least one month (71).
quire more aggressive management, while at the same As permanent recurrent laryngeal nerve injury is
time, and equally importantly, sparing the majority of uncommon when a thyroidectomy is performed by ex-
patients from unnecessary treatments and procedures. perienced surgeons, and seldom occurs asymptomati-
Therefore, for the purpose of therapeutic planning and cally before surgery, we do not recommend a routine
the definition of the best follow-up approach for pa- performance of preoperative video-laparoscopy. The
tients with DTC, assessment of the risk of disease recur- same applies to the measurement of the serum calcium
rence and progression is crucial. levels with regard to hypoparathyroidism.
When must initial surgery be performed? Recommendation 27
Thyroidectomy is indicated together with a DTC diag- Preoperative neck US is recommended, even in asymp-
nosis. Nevertheless, patients with a low life expectancy tomatic patients without palpable lymph nodes, to as-
due to an associated severe disease might be spared sess the tumor multicentrality, the presence of lymph
thyroidectomy and given palliative treatment in case node metastases, and the extrathyroidal invasion (Re-
of advanced or progressive disease. Similarly, when commendation B). No other study is routinely recom-
surgery represents a risk due to patient condition, but mended (Recommendation B).
the patient is expected to improve, thyroidectomy
might be delayed for some months, provided the tu- What must the extent of the thyroidectomy be?
mor is not progressing or growing (67). The same Total thyroidectomy is the most recommended sur-
applies to women diagnosed at the beginning of preg- gical procedure in patients with DTC. Lobectomy
nancy, who should also be subjected to monitoring may be indicated in patients with classic, unifocal,
with US. Surgery may be indicated in the second tri- sporadic papillary carcinoma ≤ 1 cm and without
mester if the tumor is growing (see Recommendation apparent lymphadenopathy or extrathyroidal inva-
19) or after labor if the tumor is stable (53). In the sion (67,72-75).
absence of contraindications, TSH levels must be su- In patients initially subjected to partial thyroidecto-
ppressed (< 0.5 mIU/L) in patients who will not un- my, surgical complementation may be avoided in cases
dergo surgery or must wait some months before the of papillary carcinoma presenting with the characteris-
surgery is performed. tics described above as well as in cases of minimally in-
Except for exceptional circumstances, any delay be- vasive follicular carcinoma and the capsulated follicular
tween DTC diagnosis and thyroidectomy is unjustified. variant of papillary carcinoma (without vascular inva-
sion) measuring up to 2 cm.
What preoperative assessment is recommended?
Recommendation 28
Preoperative US must be performed to identify the tu-
mor multicentrality, which is supportive of the choice Total thyroidectomy is the surgical procedure of choi-
of total thyroidectomy as initial treatment, as well as to ce in patients with a preoperative diagnosis of papillary
look for non-palpable lymph node metastases (26,68) carcinoma (Recommendation A).
because their presence requires modified neck dissec-
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tion. Although it is not indicated for this purpose, US Recommendation 29
results may also suggest tracheal and/or esophageal in- The indication for surgical complementation in patients
vasion by the tumor (26). Any suspicious lymph nodes initially subjected to partial thyroidectomy must take
must be assessed by FNA. into account the anatomical-pathological data in parti-
CT, MRI, esophagoscopy, or laryngotracheoscopy cular and the individual risk posed by the novel inter-
are not routinely recommended and are only indicated vention (Recommendation A).
Arq Bras Endocrinol Metab. 2013;57/4 247Thyroid nodules and differentiated thyroid cancer
What is the surgical management of lymph nodes? Recommendation 32
Lymph node metastases are frequent findings by the In patients without suspected metastases on preope-
time the diagnosis of papillary cancer is established rative US and the surgeon’s perioperative assessment,
(76). As neck palpation does not produce abnormal fin- elective dissection of the central compartment lymph
dings in most cases (77), a preoperative US and careful nodes may be considered when the tumors are > 4 cm
perioperative assessment by the surgeon are needed. or there is apparent extrathyroidal invasion (Recom-
Whenever metastases are suspected based on US or du- mendation C).
ring surgery, the patient should be subjected to a total Although the BRAF gene mutation is associated
thyroidectomy and therapeutic lymph node dissection, with greater initial aggressiveness of papillary carcino-
even in the case of tumors ≤ 1 cm, because full tumor ma, including higher frequency of lymph node metas-
resection improves prognosis (78). tases, the available data are not sufficient to rule out or
Even when preoperative US and perioperative as- indicate elective dissection of the central compartment
sessment are negative, many patients with papillary lymph nodes on the grounds of the absence or presence
carcinoma exhibit lymph node micrometastases in the of this mutation, respectively (84,85).
central compartment (79). Nevertheless, there are no
consistent data showing that elective dissection of those How must staging be performed after surgery?
lymph nodes reduces the risk of relapse. Adjuvant the
The aims of postoperative staging are as follows: 1) to
rapy with 131I and TSH suppression may help control
estimate the mortality risk; 2) to establish the risk of
the progression of eventual non-resected micrometas-
relapse; 3) to assess the quality of surgery; 4) to define
tases (80). However, such progression likely does not
the initial individualized treatment; and 5) to make the
occur naturally in most cases (81).
terms uniform and facilitate the communication among
Although some studies have reported low morbidity
associated with central compartment lymph node elec- the multidisciplinary staff that participates in patient
tive dissection (79,82), other authors found a higher treatment and follow up.
risk of transient and permanent hypoparathyroidism The staging system formulated by the American Joint
(83), even when the procedure is performed by experi- Committee on Cancer/International Union against
enced surgeons. Cancer (AJCC/UICC) based on the tumor size, extra-
The lymph nodes in the lateral compartments (II to thyroidal invasion, lymph node and distant metastases
IV) and the posterior triangle may also be affected by (TNM), and age is recommended for all tumor types
papillary thyroid cancer metastases (76). However, re- including thyroid tumors as an attempt to standardize
moval of those lymph nodes appears to exert significant the description of tumor extent. As that system does not
impact only on patients with clinically or US-detected consider other factors known to influence the progres-
metastases (68). sion and prognosis of DTC patients, its ability to predict
the persistence and relapse of these tumors is limited,
Recommendation 30 whereas it is more useful in the estimation of the mor-
tality rate associated with the disease. In any case, the
When affection of the central compartment lymph nodes tumor size, presence and extent of extrathyroidal inva-
is suspected, therapeutic dissection of this compartment sion and lymph node and distant metastases are relevant
is indicated (Recommendation A). When the presence parameters in the choice of the initial treatment.
of metastasis is confirmed in the pre- or perioperative Some histological variants such as tall and colum-
period, dissection must include the lymph nodes in the nar cells, extensively invasive follicular carcinoma, and
ipsilateral compartment (Recommendation B). poorly differentiated carcinoma exhibit more aggres-
sive behavior (72,78). Other signs of a poor progno-
Recommendation 31 sis include considerable nuclear atypia, tumor necrosis,
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When affection of the lymph nodes in the lateral com- and vascular invasion, all of which suggest lower grades
partments is suspected, therapeutic dissection of these of tumor differentiation (86).
compartments is indicated (Recommendation A). When The impact of lymph node compromise on the prog-
the presence of metastases is confirmed in the pre- or nosis is controversial. According to prevailing opinions,
perioperative period, dissection must include the central lymph node metastases that are macroscopic, present in
compartment lymph nodes (Recommendation B). large numbers or characterized by extracapsular exten-
248 Arq Bras Endocrinol Metab. 2013;57/4Thyroid nodules and differentiated thyroid cancer
sion increase the risk of relapse and mortality in patients affected margins) as well as the postoperative assess-
older than 45 years old (87,88). ment to achieve better estimates of the risk of recurren-
Therefore, we describe four categories of risk of per- ce (Recommendation B).
sistent or recurrent disease in table 5.
We excluded children and adolescents from that How are the tissues remaining after surgery quantified?
stratification, as the classification of risk should be par- Even when thyroidectomy is reported to be total,
ticularized in those cases because, despite the high fre- quantification of the remaining thyroid tissue is re-
quency of cases of disease not restricted to the thyroid, commended, especially when surgery is performed by
their long-term prognosis is excellent (67,72). a surgeon with little or unknown experience. For that
purpose, neck US is superior to scintigraphy and also
Recommendation 33 provides information on the persistence of lymph node
The initial staging of patients must be performed accor- metastases (89,90). For this purpose, a 3-month inter-
ding to the TNM system. However, the stratification of val is required between surgery and ultrasonographic
risk must also consider other anatomical-pathological assessment (90). The analysis of vascularization using
data (histological subtype, vascular invasion, free or Doppler can be helpful in the differential diagnosis of
Table 5. Stratification of the risk of recurrence
Anatomopathological data and postoperative information
Tumor size and
Lymph node
Risk extrathyroidal Distant metastasis Histology Tumor resectionb Uptake on WBS
metastasis
invasion
> 10 affected LN or
Extensive
> 3 LN with ECE or
High (any finding) extrathyroidal M1a Incomplete Distant (M1)
any metastatic lymph
invasion (pT4)
node > 3 cm
Intermediate (any 4-10 affectedLN or Aggressive subtype
> 4 cm Neck ectopic (LN)
finding) 1-3 LN with ECE or vascular invasion
≤ 4 cm with minimal
extrathyroidal 1-3 LN without ECE
invasion (pT3)
2-4 cm without
Intermediate (both
extrathyroidal 1-3 LN without ECE
findings)
invasion (pT2)
2-4 cm with minimal
extrathyroidal cN0c
invasion (pT3)
≤ 4 cm without
extrathyroidal cN0c
invasion
≤ 2 cm without
Classic, without
Low (all findings) extrathyroidal 1-3 LN without ECE M0a Complete Thyroid bedd
vascular invasion
invasion (pT1)
≤ 2 cm with minimal
extrathyroidal cN0c
invasion (pT3)
≤ 1 cm without
extrathyroidal
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invasion (pT1a)
Classic, without
Very low (all findings) 1-2 cm without cN0c M0a Complete
vascular invasion
extrathyroidal
invasion (pT1b),
single
LN: lymph nodes; ECE: LN: extracapsular extent; WBS: whole body scan.
a
Detected on clinical or radiological assessment or post therapy WBS; b Based on the surgeon’s description and postoperative assessment; c cN0: without metastases on pre- US and perioperative
assessment, with (pN0) or without (pNx) elective dissection; d Only when 131I ablation is indicated.
Arq Bras Endocrinol Metab. 2013;57/4 249Thyroid nodules and differentiated thyroid cancer
lesions in the thyroid bed and in determining whether intermediate risk of relapse (Recommendation B). With
the lymph nodes are benign or metastatic. regard to low-risk patients, ablation should be dismissed
when stimulated Tg levels are ≤ 1 ng/ml after surgery
Recommendation 34 (Recommendation B). Ablation is not indicated in cases
Measurement of thyroid remnants and postoperative with a very low risk of relapse (Recommendation B).
assessment of the neck must be preferentially perfor-
med using a Doppler US (Recommendation B). How should TSH stimulation be performed before 131I
ablation/therapy?
Recommendation 35 Human recombinant TSH is the pre-treatment proce-
Surgical reinterventions should be considered when the dure indicated for patients with conditions potentially
US shows large thyroid remnants or lymph node me- aggravated by hypothyroidism [such as heart, lung, or
tastases (Recommendation B). atherosclerotic disease, kidney failure, severe depres-
sion, old age, and weakening diseases (107)] or with
When is 131I ablation/therapy indicated after total an inability to raise endogenous TSH to satisfactory
thyroidectomy? levels (as in hypopituitarism). Even when none such
condition is present, recombinant TSH is preferable
Treatment with 131I is indicated for patients with in-
complete tumor resection or apparent metastases after when it is available in patients with complete tumor
thyroidectomy and who are not candidates for surgical resection and no apparent metastasis after thyroidec-
reintervention. In patients with apparently complete tomy because it is known to be efficacious in such
tumor resection but high or intermediate risk of per- cases (108-112). Furthermore, recombinant TSH
sistent disease (87,91), adjuvant 131I therapy impacts exhibits advantages over discontinuation of T4: the
prognosis (92) and is thus recommended. quality of life of the patients is not affected; it elimina-
131
I ablation is not indicated for very low-risk pa- tes the symptoms and eventual risk of hypothyroidism;
tients (67,72,73,75,93-95). and it is associated with shorter leaves of absence, less
In the remainder of patients, i.e., those with a low risk extrathyroidal radiation, and shorter exposure to high
of persistent/recurrent disease, ablation is controversial TSH levels (103,108,109,111,113). In the remainder
(67,96). In such cases, administration of 131I may confer of patients (incomplete tumor resection or persistent
additional benefits such as improvement of the serum metastases), discontinuation of T4 over 3 or 4 weeks is
Tg specificity and the early detection of metastasis on a still the most proper indication in the absence of clinical
whole body scan (WBS). Nevertheless, in patients with contraindications. The latter recommendation also ap-
stimulated Tg levels ≤ 1 ng/ml and no abnormalities on plies to children and adolescents because although the
an US a few months after thyroidectomy, the specificity use of recombinant TSH is safe and apparently effica-
of that marker is not affected by the remaining tissue; it cious in them (114), further studies are required.
is known that a WBS after 131I administration does not To perform 131I ablation or therapy, one ampoule of
detect metastases (97,98); and the risk of relapse is low, recombinant TSH (0.9 mg) is administered intramus-
even when 131I is not administered (90,99,100). For cularly on two consecutive days followed by 131I admin-
those reasons, this criterion suggests to dismiss ablation istration 24 hours after the second dose.
in the low-risk group (90,97-100).
Indication for 131I must also consider the cost of Recommendation 37
treatment as well as its potential adverse effects such In the presence of clinical conditions potentially ag-
as transient alterations of the gonadal function (101- gravated by hypothyroidism, recombinant TSH is the
103), acute sialadenitis (103), early menopause (104), recommended pre-treatment (Recommendation A).
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and persistent xerostomia and xerophthalmia (105) in In the absence of such conditions, the discontinuation
addition to a higher risk of second cancers (106). of T4 is recommended in patients with known tumor
persistence, as well as in both children and adolescents
Recommendation 36 (Recommendation C). In the remainder of patients, re-
combinant TSH is recommended whenever it is availa-
I is indicated for patients subjected to total thyroi-
131
ble (Recommendation A).
dectomy and with known tumor persistence or high or
250 Arq Bras Endocrinol Metab. 2013;57/4Thyroid nodules and differentiated thyroid cancer
What 131I activity should be administered? uptake and radiation dose in the lesions (121). Never-
In patients with low risk of persistent or recurrent di- theless, the influence of a low-iodine diet on the success
sease and in whom a total thyroidectomy was properly rate of ablation/therapy has not yet been demonstrated
performed, an activity of 30 mCi of 131I is efficacious in a convincing manner (121). The corresponding stu-
to achieve remnant ablation (108,109,115-118) and dies are few, and none included a long-term assessment
exhibits low medium- and long-term relapse rates of the relapse and mortality rates (121). In addition to
(67,93,117,119). In this regard, two major randomi- diet, other sources of iodine should be investigated (e.g.,
zed trials with 438 (108) and 756 (109) patients stand medications, syrups, dietary supplements, topic solu-
out. Both studies showed clearly that the efficacy of 30 tions, cosmetics). In addition, iodinated contrast agents
mCi for the purpose of ablation was the same compa- are an important source of contamination, whose com-
red to 100 mCi independent of the pre-treatment, i.e., plete elimination requires at least one month (71).
discontinuation of T4 or recombinant TSH (108,109). Administration of furosemide and/or lithium be-
When the size of the thyroid remnant is uncertain, the fore 131I may increase its uptake and the success rate
parameters to indicate an activity of 30 mCi are the of ablation performed with low 131I activity (116,118);
volume measured on US (≤ 2 g), thyroid bed uptake however, the available evidence does not suffice to re
[≤ 2% (108,109,115)], or postoperative Tg levels (97). commend it as routine.
Activities of 200 mCi or greater require caution
when dosimetry is not available, particularly in the case Recommendation 42
of elderly or patients with diffuse lung metastases, be- Despite its controversial benefit, a low-iodine diet must
cause the maximum tolerated activity is commonly ex- be prescribed due to its potentially positive effect and
ceeded in such cases (120). low cost (Recommendation B).
Recommendation 38 Recommendation 43
In low-risk patients, an activity of 30 mCi is preferable, Women of reproductive age should be subjected to
whereas a 100-mCi activity is reserved for cases with clinical and laboratory assessment (measurement of
known large tissue remnants (Recommendation A). human chorionic gonadotropin; b-hCG) to rule out
a pregnancy before administration of 131I. Pregnancy
Recommendation 39 and breastfeeding are absolute contraindications to the
In patients without apparent disease, but intermediate use of RAI (Recommendation A). Women are advised
or high risk, activity of 100 mCi is recommended (Re- to avoid conception for 6 to 12 months after RAI, and
commendation B). men are similarly advised for 3 months (Recommenda-
tion B).
Recommendation 40
What tests must be performed before and
In patients with local-regional tumor persistence, who immediately after 131I ablation/therapy?
are not candidates for surgical reintervention, activities
of 100 or 150 mCi are recommended (Recommenda- When TSH levels are > 30 mIU/l, Tg levels after total
tion B). thyroidectomy and immediately before ablation bear a
direct correlation with the presence of persistent metas-
Recommendation 41 tasis and WBS after treatment with RAI (67,97,122),
are predictive of the success of the ablation (97,123),
An activity of 200 mCi should only be considered for and behave as an important long-term prognostic fac-
adults with known distant metastases (Recommenda- tor (122,124,125). In addition, in the patients with
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tion B). elevated Tg levels after initial treatment, comparison
with the Tg levels obtained during the ablation is pre-
What other recommendations are important in 131I dictive of the clinical outcome (124,125).
ablation/therapy? WBS before RAI treatment exhibits a lower sensiti
A low-iodine diet, usually ≤ 50 µg/day for 7 to 14 days vity for metastases compared to WBS after RAI treat-
before the administration of 131I, appears to increase the ment (126) and may also be associated with a risk of
Arq Bras Endocrinol Metab. 2013;57/4 251Thyroid nodules and differentiated thyroid cancer
stunning, delayed treatment, and higher costs. Con- An activity of 100 mCi of 131I is recommended when
versely, the post-treatment WBS exhibits higher sensi- stimulated Tg levels are greater than 10 ng/ml under
tivity and is able to identify unsuspected metastases (67 hypothyroidism or 5 ng/ml after use of recombinant
,87,91,97,98,109,111,122,126). Physiological uptake, TSH and a negative WBS. An activity of 100 to 200
or false-positive WBS results after treatment with RAI mCi is recommended when WBS shows ectopic uptake,
must be suspected when Tg is undetectable or low at depending on the extent of the metastases.
the time of ablation [in the absence of anti-Tg anti-
bodies (TgAb)], when there is a lack of radiological Recommendation 47
correspondence to uptake, or when uptake occurs in In patients undergoing thyroidectomy, but whose ana-
sites unusual for metastases, particularly when isolated tomopathological data are not sufficient to establish
(127).
appropriate risk stratification, a more thorough pos-
toperative assessment is needed to determine the need
Recommendation 44 for surgical reintervention and 131I ablation or therapy
Measurement of serum Tg and TgAb must be per- (Recommendation A).
formed immediately before 131I administration (Re-
commendation B). When must external radiotherapy be included in the
initial treatment?
Recommendation 45
Recommendation 48
In patients with known anatomical-pathological and
surgical data, WBS prior to treatment with RAI is not External radiotherapy must be considered for patients
recommended (Recommendation B). with incomplete tumor resection, who are not candi-
dates for surgical reintervention, and when the tumor
Recommendation 46 remnants exhibit low 131I uptake (Recommendation B).
WBS must be performed 5 to 7 days after 131I admi-
When must T4 replacement be initiated?
nistration in any patient subjected to this therapy (Re-
commendation B). When the results of WBS after In very low-risk individuals without indication for 131I
treatment with RAI are suggestive of metastasis, it is administration, T4 replacement must be initiated imme-
recommended to complement the assessment with an diately after surgery. When recombinant TSH is used,
additional method to image the area corresponding to there is no justification to delay T4 replacement. Similar-
ectopic uptake (Recommendation B). ly, in the case of low-risk patients in whom the decision
to perform 131I ablation depends on the Tg level appro-
What is the approach in patients already ximately 12 weeks after surgery, hormone replacement
subjected to thyroidectomy but with insufficient must be initiated early. Finally, when the clinical, histo-
anatomopathological data for risk stratification? logical, and radiological data indicate the need for 131I
In this circumstance, the assessment of the thyroid re- ablation/therapy, and the 131I ablation/therapy will be
mnants and the determination of the presence of me- performed within four weeks, T4 replacement may be
tastases are important. Initial assessment comprises cli- delayed following thyroidectomy. However, when 131I
nical examination, serum Tg [T4] (i.e., without TSH ablation/therapy is scheduled for a later period, T4 re-
stimulation) and TgAb levels, neck US, and simple placement must be initiated after surgery to avoid long-
chest x-rays. Surgical reintervention must be conside- -lasting hypothyroidism, and then discontinued.
red when large thyroid remnants (128) or lymph node When 131I ablation/therapy is preceded by discon
metastases are found. When neither US nor x-rays show tinuation of T4, hormone replacement must be restarted
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abnormalities, but Tg [T4] levels are higher than 1 ng/ early, i.e., 48 hours after the administration of RAI, and
ml, it is recommended to administer 30 or 100 mCi of at the full dose to promote rapid TSH reduction (113).
131
I based on Tg [T4] levels. When the initial assess-
ment rules out persistent disease, stimulated Tg must Recommendation 49
be performed (following discontinuation of T4 or use T4 therapy must be initiated as early as possible (Re-
of recombinant TSH) together with a diagnostic WBS. commendation B).
252 Arq Bras Endocrinol Metab. 2013;57/4Thyroid nodules and differentiated thyroid cancer
What is the indicated TSH level following initial must be avoided. Third, in addition to appropriate cal-
treatment? cium and vitamin D intake (in all), periodic cardiovascu-
In patients with well-differentiated tumors, TSH su- lar assessment (all) and bone densitometry (postmeno-
ppression is an important adjuvant therapy. In indivi- pausal women) are recommended in patients subjected
duals with known metastasis, TSH suppression has an to TSH suppression for long periods of time. Finally, if
inhibitory action on tumor growth and disease pro- the TSH suppression persists, in addition to their usual
gression (67). In patients without apparent disease but therapeutic indications, beta-blockers must be consi
with elevated Tg levels, low TSH levels contribute to dered in patients with heart symptoms or morphological
the long-term negation of this marker (129). In addi- alterations, as well as the use of bisphosphonates in post-
tion, in cases without apparent disease but high risk of menopausal women with osteopenia (57,58).
relapse, TSH suppression is associated with improved To avoid long periods outside the target, it is re
outcomes (130,131). Even in low-risk patients under commended to measure TSH levels 6 to 8 weeks after
full remission, TSH levels persistently over 2 mIU/ml the onset of replacement therapy or after any change in
are associated with worse long-term progression (132). the dose or commercial formulation of T4 and every six
Subclinical thyrotoxicosis is associated with bone months once the desired levels are achieved, provided
mass compromise, especially among postmenopausal the dose is kept unchanged.
women (57,58,133), and morphological and functional
heart disorders (57,58), which have more clinical reper- Recommendation 50
cussions among older adults. To minimize the adverse The level of TSH suppression must be individuali-
effects of suppressive therapy with T4, some steps are zed according to the ongoing disease state (Recom-
important. First, clinicians should pay attention to the mendation B). Measures to monitor and prevent the
fact that the TSH target must be individualized and sub- negative effects of TSH suppression must be applied to
jected to constant reassessment (134), taking the pres- patients subjected to TSH suppression for long periods
ence of metastasis, Tg levels, and risk of relapse into ac- of time (Recommendation B).
count (Figure 2). Second, truly undetectable TSH is not
necessary, and high serum T4 and especially T3 levels, What are the recommendations relative to the
method for thyroglobulin measurement?
Thyroidectomy
Measurement of Tg is not a trivial laboratory exam (135).
Although a number of limitations are minimized by highly
sensitive immunometric methods, others remain (135):
Without 131| ablation | 1. Lack of international standards, resulting in va-
131
riability of the available methods.
TSH 0.5-2 mIU/L RxWBS
2. Excessively high inter-assay variability, espe-
cially when we consider the usual interval bet-
Metastases Negative ween sample collections during the follow up
of patients with differentiated carcinoma (6 to
TSH ≤ 0.1 mIU/L Low risk: TSH 0.1-0.5 mIU/L 12 months). Therefore, to reduce the inter-as-
High risk: TSH ≤ 0.1 mIU/L
say error, the laboratories should keep samples
frozen for at least one year to process the older
Control assessment
sample together with the newer one.
3. Possibility of a “hook effect”, especially in the
Metastases Elevated Tg or TgAb Complete remission immunometric assays, leading to inappropria-
(without apparent
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disease) tely low results in patients with very high Tg
levels. To avoid this effect, the tests should be
Low risk: TSH 0.1-0.5 mIU/L Low risk: TSH 0.5-2 mIU/L systematically performed in two steps.
High risk: TSH ≤ 0.1 mIU/L High risk: TSH 0.1-0.5 mIU/L
in the first 5 years 4. The presence of TgAb in the serum can elicit fal-
se low Tg results in immunometric assays (136).
Figure 2. Recommended TSH levels after initial treatment in patients with
differentiated thyroid cancer.
Therefore, investigation of TgAb is mandatory,
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